Process for the manufacture of sintered multifilamentary structures



July 4, 1961 G. G. THOMAS 2,991,147

PROCESS FOR THE MANUFACTURE OF SINTERED MULTIFILAMENTARY STRUCTURES Filed July 16, 1958 Inventor G W/L YM 6272/?00 flan/95 I Attorney PROCESS FOR THE MANUFACTURE OF SIN- TERED MULTIFILAME'NTARY STRUCTURES ,Gwilym Garrod Thomas, Pontypool, England, assignor to British Nylon Spinners Limited, Pontypool, England Filed July 16, 1958, Ser. No. 749,004

Claims priority, application Great Britain July 16, 1957 I: 9 Claims. (Cl. 18-54) The present invention relates to the manufacture of filamentary structures of a macromolecular synthetic linear polymer andmore particularlyto making said structures by a process of melt-spinning.

,In the manufacture of multifilament yarn from synthetic linear polymers, such as polyamides, e.g. polyhexamethyleneadipamide, by melt-spinning, it is the practice to gather together the bundle of filaments issuing substantially vertically downwards from a multihole spinneret by passing all the filaments through a guide when they have cooled at least sufficiently to avert any danger of adherence occurring when they touch. The filaments thus converge towards the guide and the latter is accordingly known as a convergence guide. Conveniently the cool- ;ing is eifected by an air stream. The filaments are then often exposed to steam in order to increase their water content before they are wound up. Usually the resulting multifilament yarn, which is undrawn and has no twist, is submitted to a process of drawing in the solid state, in order to improve the textile properties, especially the .tenacity, and twisted to a greater or less extent as re- .quired. LIthas now been foundthat by causing the filaments to touch tangentially a convex water surface, before they reach the convergence guide but when already fairly "close together, the filaments suddenly make contact with one another on the water surface, grouping themselves into one or more composite clusters and becoming sintered together and simultaneously quenched. In this way they are permanently united in the aforesaid groups and constitute a novel yarn. The groups assume various forms depending on the operational conditions as described below. Thus the filaments may align themselves in a single row, becoming sintered together to form a ribbon, or they may form several clusters of twos and threes. In

any case it will be seen that in accordance with the invention the filaments converge at the convex water surface instead of at the convergence guide, as in previously known processes. It may well be supposed that the clustering or coming together of the filaments at the water surface is due largely to the high surface tension; be

.this-as it may, however, the essence of the present process seems to lie in the simultaneous or substantially simultaneous coalescence and quenching of the filaments at the water surface whereby adjacent filamentsbecome sintered together.

The convex water surface may conveniently be presented to the filaments by causing water to exude or ooze froin a narrow horizontal slit positioned below the spinwater is slowly fed. The resulting slit edge may be straight or curved, for instance, in the arc of a circle, the filaments then running against the water edge or bulge extend-ing along the curve.

The slit edge with the projecting water bulge or meniscus 5 must not be too far below the spinneret or else the filaments will be too cold, when they reach it, to sinter together. This is shown by the following figures:

Yarn Polyhexamethylene adipamide.

No. of filaments 10.

Denier when spun 95.

Rate of spinning (measured at wind up 3,500 ft./min.

Distance of water sur- Degree of sintering face below spinneret filangnts firmly fused together.

. filaments lightly sintered together but could be peeled apart.

32 inches no fusion observed.

' Nor should the slit edge be too near the spinneret, because the filaments then become difiicult to draw. The process of drawing can, however, be improved by increasing the supply of Water to the slit edge. In general, the greater the quantity of water applied to the yarn, the better the drawing performance, provided the water sup- "pliedfdoes not spoil the formation of the cake when the melt-spun yarn is wound up. For example, in processing yarn of spun denier 228 at a wind up speed of 2,000 ft./min., a suitable rate of applying Water to the yarn as it passes over the convex water surface, is 2 cc./mi n. For this purpose a slit may be employed which comprises two edges with a gap of 0.005 inch between.

Accordingly this invention relates to a process for the manufacture of filamentary structures comprising meltspinning a macromolecular synthetic linear polymer into a plurality of filaments which are extruded substantially vertically downwards and wound up by conventional means, characterised in that the filaments are caused to glide tangentially or nearly so, through a convex aqueous surface or meniscus, whereat they converge into and form one or more clusters and are quenched whereby they become united or sintered together where they touch in the form of a composite cluster or composite clusters.

The position of the filaments, as they pass downwards, may be controlled by auxiliary guides, air blasts or other known means, as may be required. It is found, however,

' that the convergence guide referred to above is not usually necessary when the filaments all form one cluster. More than one spinneret may be employed if desired.

The aqueous surface may advantageously be water, but it is permissible to include dyes or pigments or other textile agents, provided the surface tension of the water is not appreciably impaired.

As already indicated, the convex aqueous surface or meniscus is conveniently maintained by letting water exude from a narrow horizontal slit. The gap therein may amount to l-8 thousandths of an inch. Various forms of this slit are shown in FIGURE 1 of the accompanying diagrammatic drawings, .which are intended to illustrate but not limit the invention. Thus at 1 is indicated a slit edge in the form of two straight lines 2, 3, at an angle of '8'5 joined by an are 4, Of'%,2 inch radius, which the straight lines meet tangentially. 5 is the water supply pipe and the concavity of the arc faces the filaments. In FIGURE 2, numbered similarly, the filaments 6 are shown passing over the aforesaid slit edge. 7 is the convergence guide. The contour of the slit edge may also constitute sections in FIGURE 3 of the accompanying drawings,

where there are illustrated a linear group (No. 10), a group partly anular and partly linear (No. 11), and an annular group (No. 12). Cross-sections of the composite clusters of FIGURE 3 after drawing are shown in FIGURE 4, cross-sections Nos. 13, 14 and 15 corresponding respectively to Nos. 10, 10 and 12 of FIGURE 3. It will be observed that the effect of drawing is to flatten the.v filaments into ribbons which are one or two filaments thick. It may be added that in the case of curved concave edges an increase in the water flow is found to favour the formation of clusters of annular cross-section rather than clusters of linear cross-section.

One or more slits may be employed and it is often found advantageous to offset the slit from a position directly below the extrusion point towards the filaments.

FIGURE illustrates diagrammatically a process of melt-spinning the polymer into a plurality of filaments which are extruded substantially vertically downwards and wound up by conventional means, characterized in that the filaments are caused to glide tangentially or nearly so, through a convex aqueous surface or meniscus, whereagainst they are urged by an air blast and whereat they converge into and form one or more clusters and are quenched whereby they become united or are sintered together where they touch in the form of a composite cluster or composite clusters. In FIG- URE 5, the numeral 21 identifies a conventional spinneret, from which issue a bundle of filaments 6 into an air stream delivered by pipe 23. The arrows show the direction of the air stream which accordingly urges the filaments from left to right in the drawing, and consequently against the aqueous surface or meniscus formed by the member 1 before the filaments reach the convergence guide 7. Members 1 and 7 have been shown on a larger scale in FIGURE 2. From the guide 7 the filaments proceed via the rolls 25 and 27 to the bobbin 2:; where they are wound up by conventional means.

Besides polyamides, already mentioned, the synthetic linear polymer may consist of a polyester, for instance, polyethylene terephthalate. The filaments which converge into clusters, may differ in respect of the polymer of which they consist, and/or their denier. Thus, for example, polyhexamethylene, adipamide filaments of different deniers may be sintered together.

The present invention includes filamentary structures containing one or more composite clusters of filaments and made by the above process, which filamentary structures constitute a novel yarn. Fabrics woven or knitted from such yarn are distinguished by their crispness and the. relative absence of soapy or slippery feel.

The following examples are intended to illustrate but not limit the invention.

Example 1 The filaments of polyhexamethylene adipamide are melt-spun downwards from a spinneret having holes of diameter 0.009 inch in a straight line. The filaments are wound up by conventional means at 3,500 ft./min. Thespun denier is 95. The filaments leaving the spinneret converge to form 3 composite filaments at a wet edge, described below, against which the filaments are urged by a transverse air stream. The wet edge which is situated 10 inches below the spinneret face, consists of a straight horizontal metal slit 2 inches widethe gap of the slit-.beingS .thousandths of an inch. The slit from which water exudes, forms the end of a pipe, the rate of water supply being 1.5 cc. per min.

The resulting 3-filament yarn is drawn at a ratio of 3.31, and given a twist of 0.75 turn per inch. It has the following properties:

Denier 30.

Tenacity 4.9 gms. per denier. Extensibility to break 21%. Dynamic coeflicient of friction determined against a glass pin at 1,075 ft./rnin 0.40.

The corresponding friction figure for 30 denier yarn of 10 filaments, i.e. yarn melt-spun without using the present process, is 0.51.

When the present yarn is woven as weft in a plain weave with a 30 denier (10 filament) olyhexamethylene adipamide yarn warp, a crisp non-slippery fabric results.

Example 2 Example 1 is repeated except that a spinneret is employed having 21 holes two parallel rows of 10 and 11 holes respectively. The wet edge, instead of being straight as in Example 1, has two straight arms at right angles, each 1 inch long, and is positioned 12 inches below the spinneret. The. 21 filaments urged against the wet edge by a transverse air blast, converge together and become united in the form of a ribbon mainly 2 filaments thick. For this purpose the rate of water supply is adjusted at 2 cc. per min.

Example 3 The filaments are found to converge at the wet edge to form a yarn of five composite filaments, comprising respectively 2, 3, 3, 4 and 9 of the original individual filaments. The yarn is drawn at a ratio of 4.05 into a fabric as described in Example 1, and given a twist of 0.75 turn per inch. The denier is 60. When woven a very crisp texture results. On dyeing the resulting fabric with Serisol Brilliant Blue BG the surface obtained is not of uniform appearance but exhibits attractive light flashes.

Examples 4 and 5 Polyhexamethylene adipamide is spun from a l5-holed spinneret in which the holes of diameter 0.012 inch are evenly distributed about a circle of radius inch. A slingle filament yarn is obtained under the following conitions:

Example 4 5 Rate of wind up Denier as wound up 440 Wet edge Distance of wet edge from spinneret.

Distance by which wet edge is offset from a point below the centre of the spinneret towards the. yarn and wsizurce of rliir.

a an supp y Air current 2450 itJmin. Arc of 360 inch Arc of 56a inch radius. 10 inches 1 inch 2 inches.

20 ctr/min I 3 ccJmtu. 6 cu. ftJmin...

106cu. itJmin.

Example 4 1;

Form of composite Ribbon having cross- Ribbon oi cross-seccluster of yarn. section which is 7-8 tion which is about a filaments wide and filaments wide 2 filaments thick. and 1-2 filaments V thick.

Denier. 105 110.

Tenacityin gins/denier. 4.6 5.0.

Extensibility to break. 28% 32%.

The yarns are woven separately as wefts across warps of polyhexamethylene adipamide yarn having 20 filaments (3 denier each) twisted together with 7 Z turns per inch. After scouring with /2 aqueous sodium carbonate the fabrics are dyed with Multamine Black B.

The fabrics have a novel appearance, due to pronounced lustre variations, ascribed to difference in light reflection from difierent sides of the ribbon-like filaments. The fabrics have crease recovery angles greater than 150 when determined by the method test for the Recovery of Fabrics from Creasing described in the Journal of the Textile Institute (Proceedings), 1957, vol. 48, at pages 326-329. Moreover they spring back after bending much more quickly than comparable fabric made from nonsintered yarn (i.e. in which the warp was as before and the weft comprised -filament polyhexamethylene adipamide yarn of 100 denier with Z turn per inch twist).

Example 6 Polyhexamethylene adipamide is spun from a l5-holed spinneret, in which the holes have a diameter of 0.012 inch and are in 3 groups of 5 in the same straight line. The distance between adjacent holes in each group is Ms inch and the distance from the centre hole of the middle group of 5 to the centre hold of either of the other groups is inch. All distances are measured from the centres of the holes.

A triple filament yarn is obtained by causing the filaments to converge on 3 wet edges under the following conditions:

Rate of wind-up 950 ft./min. Wet edges Arcs of inch radius. Distance of wet edges from spinneret 10 inches.

Distance by which each edge is offset from a point below the centre hole of the corresponding group of spinneret holes towards the yarn and source of air 1%. inches.

Water supply to each edge 1.8 cc./min. Air current 150 cu. ft./min.

The triple filament yarn is drawn at a ratio of 4.53 with insertion of 0.75 2 turns per inch at a drawing speed of 390 ft. per minute giving yarn with the following physical properties:

Denier 101 Tenacity gms. per denier 5.3

Extensibility to break percent 23 Example 7 Polyhexamethylene adipamide is spun from a 9-holed spinneret, the holes of diameter 0.009 inch being in 3 groups of 3 in the same straight line. The distance between adjacent holes in each group is inch, and the distance from the centre hole of the middle group to the centre hold of either of the other two groups is /s inch, all distances being measured from the centres of the holes.

A triple filament yarn is obtained by causing the fila- 6 ments to converge on 3 edges under the following conditions: i

Rate of wind-up 1200 ft./min. Wet edges Arcs of ,6 inch radius. Distance of wet edges from r i spinneret 10 inches. Distance by which each edge is ofiset from a point below the centre hole of the corresponding group of spinneret holes towards the yarn and source of air 1 /2 inches.v Water supply to each edge l cc./min Air current 106 cu. ft./min.

The triple filament yarn is drawn at a ratio of 4.47 with insertion of 0.75 Z turns per inch at a drawing speed of 390 ft./min. giving yarn with the following physical properties:

Denier 60.2 Tenacity gms. per denier 5.4 Extensibility to break percent 25 A plain weave fabric is made from the drawn yarn; the fabric is very stiff.

Example 8 Polyhexamethylene adipamide is spun from an 8-holed spinneret, the holes being in 2 groups of 4 in the same straight line. The adjacent holes in each group are 43 inch apart. The distance between the two groups, measured from the nearest hole in each group is /2 inch. The two nearest holes in each group are of 0.012 inch diameter, the other holes being of 0.009 inch diameter.

The two-filament yarn is obtained by causing the filaments to converge in two groups of 4 on a single straight wet edge under the following conditions:

Rate of wind-up 2000 ft./min. Denier as wound up 120. Wet edge Straight, parallel to line of holes in spinneret and 10 inches below, ofiset 1% inches from a point below centre of the spinneret towards the yarn and source of air.

Water supply to edge 3.5 cc./min

Air current 7 cu. ft./min.

The two-filament yarn thus made is drawn at a ratio of 3.48 with insertion of 0.75 Z turns per inch at a drawing speed of 833 ft./min. giving a yarn with the following physical properties:

Denier 45 Tenacity gms. per denier 3.2 Extensibility to break percent 20 What we claim is:

l. A process for the manufacture of sintered multifilamentary structures which consists essentially in the steps of melt-spinning a macromolecular synthetic linear polymer and extruding the same downwards as a plurality of independent filaments; urging said filaments, while independent of each other, and while still incompletely solidified, directly into substantially tangential contact with a convex aqueous surface; whereby said filaments are caused to cluster together due largely to the high surface tension of the said aqueous surface; gliding said filaments through said surface whereby the clustered filaments are quenched and the same are substantially simultaneously sintered together at points of contact with one another to form a composite sintered multifilament structure, and thereafter winding up said structure.

2. Process as claimed in claim 1 wherein the convex aqueous surface is produced by exuding water from at least one narrow horizontal slit.

3. Process. asclaimed inclaim 2, wherein the horizontal slit is in the form of an are having its concavity facing the filaments.

4. Process as claimed in claim 3, including urging the filaments, as they pass downwards, against the narrow horizontal slit by an air blast.

5. Process as claimed in claim 4, wherein the, horizontal slit is offset from a position directly below the extrusion point towards the filaments and source of air.

6. Process as claimed in claim 1, wherein the macromolecular synthetic linear polymer is a polyamide.

7. Process as claimed in claim 6, wherein the polyamide is polyhexamethylene adiparnide.

8. A process as in claim 1, wherein the aqueous surface is stationary.

UNITED STATES PATENTS 796,7.40 Linkmeyer Aug, 8, 1905 2,041,798 Taylor May 26, 1936 2,072,926 Taylor May 9, 1937 2,804,645 Wilfong Sept. 3, 1957 2,851,732 Sharp Sept. 16., 1958 

1. A PROCESS FOR THE MANUFACTURE OF SINTERED MULTIFILAMENTARY STRUCTURES WHICH CONSISTS ESSENTIALLY IN THE STEPS OF MELT-SPINNING A MACROMOLECULAR SYNTHETIC LINEAR POLYMER AND EXTRUDING THE SAME DOWNWARDS AS A PLURALITY OF INDEPENDENT FILAMENTS, URGING SAID FILAMENTS, WHILE INDEPENDENT OF EACH OTHER, AND WHILE STILL INCOMPLETELY SOLIDIFIED, DIRECTLY INTO SUBSTANTIALLY TANGENTIAL CONTACT WITH A CONVEX AQUEOUS SURFACE, WHEREBY SAID FILAMENTS ARE CAUSED TO CLUSTER TOGETHER DUE LARGELY TO THE HIGH SURFACE TENSION OF THE SAID AQUEOUS SURFACE, GLIDING SAID FILAMENTS THROUGH SAID SURFACE WHEREBY THE CLUSTERED FILAMENTS ARE QUENCHED AND THE SAME ARE SUBSTANTIALLY SIMULTANEOUSLY SINTERED TOGETHER AT POINTS OF CONTACT WITH ONE ANOTHER TO FORM A COMPOSITE SINTERED MULTIFILAMENT STRUCTURE, AND THEREAFTER WINDING UP SAID STRUCTURE. 